Fair Value Measurements, Recurring (Details) - Fair Value, Recurring [Member] - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Assets
Investments in AFS debt securities	$ 27	$ 26
Total gross fair value, assets	983	529
Effect of counterparty netting	(822)	(402)
Effect of cash collateral netting	(22)	0
Net carrying value on balance sheet, assets	139	127
Liabilities
Blending program obligations	140	13
Total gross fair value, liabilities	1,033	464
Effect of counterparty netting	(822)	(402)
Effect of cash collateral netting	(59)	(46)
Net carrying value on balance sheet, liabilities	152	16
Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	88	93
Commodity Contracts [Member]
Assets
Derivative contracts	867	402
Effect of counterparty netting	(822)	(402)
Effect of cash collateral netting	(22)	0
Derivative contracts, net assets	23	0
Cash collateral received not offset	0	0
Liabilities
Derivative contracts	881	448
Effect of counterparty netting	(822)	(402)
Effect of cash collateral netting	(59)	(46)
Derivative contracts, net liabilities	0	0
Cash collateral paid not offset	(55)	(71)
Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	1	2
Liabilities
Derivative contracts, not subject to netting	8	3
Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		6
Liabilities
Derivative contracts, not subject to netting	4
Level 1 [Member]
Assets
Investments in AFS debt securities	4	6
Total gross fair value, assets	955	503
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	885	448
Level 1 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	84	89
Level 1 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	867	402
Liabilities
Derivative contracts	881	448
Level 1 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	0	0
Liabilities
Derivative contracts, not subject to netting	0	0
Level 1 [Member] | Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		6
Liabilities
Derivative contracts, not subject to netting	4
Level 2 [Member]
Assets
Investments in AFS debt securities	23	20
Total gross fair value, assets	24	22
Liabilities
Blending program obligations	140	13
Total gross fair value, liabilities	148	16
Level 2 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	0	0
Level 2 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Level 2 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	1	2
Liabilities
Derivative contracts, not subject to netting	8	3
Level 2 [Member] | Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		0
Liabilities
Derivative contracts, not subject to netting	0
Level 3 [Member]
Assets
Investments in AFS debt securities	0	0
Total gross fair value, assets	4	4
Liabilities
Blending program obligations	0	0
Total gross fair value, liabilities	0	0
Level 3 [Member] | Assets Held in Trust [Member]
Assets
Investments of certain benefit plans	4	4
Level 3 [Member] | Commodity Contracts [Member]
Assets
Derivative contracts	0	0
Liabilities
Derivative contracts	0	0
Level 3 [Member] | Physical Purchase Contracts [Member]
Assets
Derivative contracts, not subject to netting	0	0
Liabilities
Derivative contracts, not subject to netting	0	0
Level 3 [Member] | Foreign Currency Contracts [Member]
Assets
Derivative contracts, not subject to netting		$ 0
Liabilities
Derivative contracts, not subject to netting	$ 0